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Testing the equivalency of ultraviolet light and chlorine for disinfection of wastewater to reclamation standards
Author(s) -
Oppenheimer Joan A.,
Jacangelo Joseph G.,
Laîné JeanMichel,
Hoagland John E.
Publication year - 1997
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143097x125137
Subject(s) - effluent , wastewater , chlorine , fecal coliform , chemistry , ultraviolet light , ultraviolet , pulp and paper industry , environmental chemistry , ceriodaphnia dubia , fouling , environmental science , environmental engineering , toxicity , water quality , acute toxicity , materials science , biology , ecology , optoelectronics , organic chemistry , photochemistry , engineering , biochemistry , membrane
Full‐scale ultraviolet (UV) light and chlorine disinfection systems were operated in parallel using nitrified and partially denitrified tertiary treated wastewater effluent. A UV dose of 75 mW · s/cm 2 reduced the concentration of fecal coliforms, enterococci, fecal streptococci, MS2 bacteriophage, and poliovirus by four logs. A higher dose was needed to reduce the concentration of heterotrophic plate count (HPC) by four logs and to achieve a total coliform value ≤2.2 MPN per 100 mL within a consecutive 7‐day period as required by the most restrictive California Wastewater Reclamation Criteria (CWRC). The cleaning frequency needed to maintain a minimum operational UV dose was assessed by constructing a lamp fouling curve describing reduction in UV intensity as a function of elapsed time since lamp cleaning. Substitution of UV light for chlorine disinfection eliminated formation of trihalomethanes, reduced formation of aldehydes, and formed a mid‐polarity unidentified peak at a bench‐scale dose of 2 800 mW·s/cm 2 The unidentified UV peak was not detected at a full‐scale dose of 188 mW·s/cm 2 . No chronic toxicity was observed for the full‐scale UV irradiated effluent; a decline in the reproductive rate of Ceriodaphnia dubia was observed for the full‐scale chlorinated effluent.